Abstract PD15-02: PD15-02 Long Term Outcome in Patients with Nodal-Positive Breast Cancer Treated with Sentinel Lymph Node Biopsy Alone After Neoadjuvant Chemotherapy

Abstract

Abstract Importance: The use of neoadjuvant chemotherapy (NAC) in the clinical care of breast cancer patients has increased considerably over recent years especially in node positive cases. For patients who have axillary nodal metastases prior to NAC, the prevailing standard of care is to undergo an axillary lymph node dissection (ALND), regardless of response to therapy. Sentinel lymph node biopsy (SLNB) has yet to be accepted as the standard staging procedure in patients who had clinical complete response in the axilla following NAC. This is due to the presumed high false negative rate associated with SLNB in such scenario. But there are limited data on the long term outcome of these patients who are only treated with SLNB alone. Aim: A retrospective cohort study comparing the long term outcome of breast cancer patients with clinically node positive disease (N1) but turned clinically node negative (N0) following NAC, receiving SLNB alone versus ALND. Methods: Patients who had pathologic proven N1 breast cancer (before NAC) treated with NAC and turned clinically N0 from January 2009 to December 2014 were identified from Asan Medical Center breast cancer database in South Korea. Primary endpoint was axillary recurrence rate (ARR) and secondary endpoints were disease-free survival (DFS) and overall survival (OS). These outcomes were reported for patients who had SLNB alone versus ALND. Results: 561 patients with clinically stage N1 (cN1) cancer treated with NAC and turned clinically stage N0 (cN0) were identified. 253 (45.1%) patients received SLNB only while 308 (54.9%) patients had ALND. The clinicopathological features of these patients were illustrated in Table 1. Majority of these patients received adjuvant radiotherapy, 81.2% in the SLNB group and 76.5% in the ALND group. In the pathologically stage N0 (ypN0) group, at a median follow up of 69 months, ARR was 3.0% in the SLNB only group and 1.7% in the ALND group (p=0.704). DFS and OS were not significantly different between patients with SLNB alone versus ALND (p= 0.561 and 0.810 respectively). Median number of SLN harvested in the SLNB only group is 5 (range 1 -17). In the pathologically stage N1 (ypN1) group with only 1-2 lymph node positive for metastasis, at a median follow up of 66 months, ARR was 5.8% in the SLNB group and 4.7% in the ALND group (p=0.768). There was no significant difference in DFS and OS between the SLNB and ALND group (p=0.537 and 0.645). In the SLNB only group, the median number of positive lymph node was 1 (range 1-2), the median number of sentinel lymph node was 6 (range 2-18). Conclusion: In cN1 breast cancer patients who were converted to cN0 following NAC, axillary recurrences were rare. No statistically significant differences were noted in DFS and OS between patients with SLNB or ALND. Our findings suggest that these patients may be safely treated with SLNB only, even when there are up to 2 positive SLNs. Table 1 Clinicopathological features of breast cancer patients with nodal disease and NAC Citation Format: Sue Zann Lim, Tae-Kyung Yoo, Sae Byul Lee, Jisun Kim, Il-Yong Chung, Beom Seok Ko, Jong Won Lee, Byung Ho Son, Sei Hyun Ahn, Hee Jeong Kim. PD15-02 Long Term Outcome in Patients with Nodal-Positive Breast Cancer Treated with Sentinel Lymph Node Biopsy Alone After Neoadjuvant Chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD15-02.